Process of making composite conductors.



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ELECTRIC COMPANY, A .COR POB ATIO N OF NEW YORK.

coonrnen, or SCHENECTADY, Nnwronx; n'ssmuon Tournamrnocnss or nnxme.comrosrrn connucrona To all whom it may concern: I

Be it known that I, WILLIAM D. Coonncn, a citizen 'of the United States,residing at Schenectady, county of Schenectady, State of New York, haveinvented certain new and useful Improvements in Processes of Mak-"ingGomposite Conductors, of which the following is a specification.

My present invention has for its object'- the production of refractoryconductors suitable for use in incandescent electric lamps, electricfurnaces, and other appara tus where electrical energy is transformedinto heator light-'- Myimproved conductorlconsists in part of refractorymetal',such as tungsten, and

possesses some of thequalities of a pure tungsten conductor. It has theadvantage,

however, of a high specific resistance; so high. in fact thatincandescent lamps can be built for commercial voltages with but asingle filament loo The filament is of such composition that it isstrong and comparativelyrigid even at the exceedingly high:

temperatures incident to efficient operation inalama 1 The d dtailsof'my improved refractory conductor and of the procedure by which it maybe made and used, are set forth in detail in the accompanyingdescription,

which should ,be taken in conjunction with I the accompanying drawing.In'this descrip .t1on, I have disclosed my invention with.specialreference to its application to the ductors for other purposesas .for use in eleca tric making of filamentary conductors forincandescent lamps; but the steps disclosed are equally app icable tothe making of confurnaces'. As a basis orcore for my improved composi'teconductor, I utilize a threadof thoria or similar refractory oxid. Suchthreads can be made by mixing pureand' finely di- H been produced on thecopperlated thorla 10.0

videdthoria with water and then squirting under pressure'throughadie. Ifdesired, a small quantity of carbonaceous binder 'may be mixed with thethoria 'rior to the squirting operation, though if and leave behindnothingbut pure thoria.

I Specification of-Letters ratent. 7 Application and September 23',1903; smelled-154,449.

1s is'used I prefer" to heat the squirted threads with' anopenfiame'toburn out the carbon of the binder this hightempe panyingdrawing. In the drawing shown an apparatus whereby the thoria threadsPatented Dec. '5, 19 11.

may be'spattered with copper by virtue of I the disintegrating action ofan electrical dis: charge passed through a poor vacuum.

The apparatus consists of an envelop 1. connected permanently to'avacuum pump.

and exhaustedtoa pressure amountingto I that of about 1 mm. of mercuryafter having been washed out with hydrogen to removeoxidizing gases. Attheto of the envelop issu ported a copper bloc 2 provided with eectrical connections to render it serviceable as cathode for anelectrical discharge. The corresponding anode 3 is passed through-theside of the envelop or otherwise suitably arranged. When currentispassedfrom anode to cathode, copper is disintegrated from block 2 and isspate tered or deposited on any object placed underneath. This henomenonis well understood and there ore needs no further exlanation. "After thethoria threads have een coated with copper as above described, they willconduct current through the copper coating. a

According to the next step in my process,

the copper coated thoriathreads are mountedin an envelop andthere givena coating 7 I of tungsten or molybdenum. This coating can beconveniently efie'cted according to' the method disclosed by.DeLodyguine in United States Patent No. 575,668, issued January 19,1897. According to the process there disclosed, the conductors-to becoated are heated with current in an atmosphere consisting. of a mixtureof hydrogen and a volatile compound of a refractory metal,

such as the oxychlorid of tungsten. The

heated conductor serves to decompose the oxychlorid with depositions ofmetallic tungsten on the conductor- After a ooherent shell-of tungstenor similar metal has threads, the conductor can be eated in hydrogen orin a mixture of hydrogen and nitrogen or in a vacuum to vaporize anddistil the copper from the conductor. The coppears to come out withoutalloying i0 consolidation of the tungsten rior to the liberation of allthe copper. A er the copper has beenremoved, the temperature oftreatment can be raised by increasing the current and can be continueduntil the tungsten layer on the thoria thread has been sintered andshrunk into a dense and homogeneous shell.

The composite filament above described has a high-specific resistanceand, owing to the rigidity of the thoria at high temperatures, is strongand not liable to distortion when used in a lamp. Single loop lampshaving commercial voltages are altogether feasible though my inventionis not llmited in its application to lamps of any particular type orsize.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

l. The method which consistsdn reducing a thread of refractory oxid,coatmg said oxid with a conductor, treating the body so formed to coverit with refractory metal, and subsequently heating to a higher temperature to drive out with which the oxid was initially coated.

2'. The method which consists in shaping threads of refractoryqmaterial,coating said threads. to produce a conductive body, depositing thereon acoating of tungsten and temperature to drive out the conductive layerthen driving out of said conductor all components except tungsten andthe original refractory material. 3. Themethod threads ofthoria, coatingwith a metal, coating again with a more refractory metal, and thenheating the conductor so produced to a temperature sufficient to driveout the less refractory metal and leave a composite filament of thoriainclosed in a shell of'inore refractory meta i. The method whichconsists in shapinga thread of thoria, coating said thread with copper,depositing on said copper a layer of tungsten, and then removing said"copper.

which consists in shaping to leave a composite filament of thoria in- Iclosed in a shell of tungsten.

5 The process which consists in producin a thread ofrefractory material,coating said thread with conductive material, treatin the resulting bodyto cover it with highly re ractory material, and heating to a high saidconductive material.

In witness whereof, I have hereunto set my hand this 21st damfSeptember, 1908.

.WILLI Witnesses:

BENJAMIN B. HULL, MARGARET E. Woommr.

n. ooomnen. 4

